Turns out this abilitly differs between families. The datasheet guarantees that a sensor is able to sink at least 4 mA at 0. Providing a current of 4 mA 1. Alternatively, It is a fake if the date--batch combination printed on the case of the sensor is not in the Maxim database need to ask Maxim tech support to find out. Note that there are counterfeits that use "authentic" date--batch combination. Note that none of the points above give certainty that a particular DS18B20 is an authentic Maxim product, but if any of the tests above indicate "fake" then it is most defintely counterfeit .
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Turns out this abilitly differs between families. The datasheet guarantees that a sensor is able to sink at least 4 mA at 0. Providing a current of 4 mA 1. Alternatively, It is a fake if the date--batch combination printed on the case of the sensor is not in the Maxim database need to ask Maxim tech support to find out.
Note that there are counterfeits that use "authentic" date--batch combination. Note that none of the points above give certainty that a particular DS18B20 is an authentic Maxim product, but if any of the tests above indicate "fake" then it is most defintely counterfeit . What families of DS18Blike chips can I expect to encounter?
The separation into families is based on patterns in undocumented function codes that the chips respond to as similarities at that level are unlikely to be coincidental . Family D1 seems to be fading from sight, having been replaced by Family D2. Chips of Family A2 were a rare find, behave surprisingly similar to authentic chips but have poor temperature accuracy.
None had sensors of Family A or C. Neither origin nor price were indicators of sensor Family. In the ROM patterns below, tt and ss stand for fast-changing and slow-changing values within a production run , and crc is the CRC8 checksum defined in the datasheet . All photos are at the same scale, approx. We broke the TO case open with pliers, detached the die from the plastic case by boiling in colophony, and removed the colophony with acetone in an ultrasonic bath.
Photos were taken with a rather ancient USB camera. All other families are clones. Note the similarities between the dies of Families D1 and D2 consistent with their similarity in software and the signifcant differences between Families B1 and B2 as opposed to their similarity in software. Returns "Trim1" and "Trim2" values if queried with function codes 0x93 and 0x68, respectively .
The bit patterns are very similar to each other within a production run . Trim2 is currently less likely to equal 0xff than Trim1 . Trim2 was 0xDB or 0xDC since at least , and has been 0x74 since the fall of all with C4 die . Trim1 and Trim2 encode two parameters .
Within a batch, the offset parameter seems to spread over 20 to 30 units while all sensors within the batch share the same curve parameter .
The offset parameter shifts the temperature output over a range of approx. Temperature offset of current batches is as shown on the Maxim FAQ page, i. Very little if any temperature discretization noise . Polling after function code 0x44 indicates a spread of ms between sensors for a bit temperature conversion at room temperature .
Conversion time is easily repeatable for individual chips. Lower resolutions cut the time in proportion, i. The trim parameters affect the conversion time. It appears the chip returns a temperature of Note that the datasheet clearly states that Vcc is to be tied to GND in parasitic mode.
Obtained no probes containing these chips on ebay or AliExpress in , but obtained chips from one vendor in If I were to make a wild guess I would say these chips were diverted somewhere toward the end of the Maxim production pipeline stolen? Fun fact: the vendor advertised these chips as QT18B20, so as sold these were actually counterfeits of DS18B20 clones. These chips are marked as produced in Thailand rather than Philippines. ROM pattern : tt-tt-Cscrc The chips follow the description of Family A above with the following exceptions : Both alarm registers are set to 0x00 scratchpad bytes 2 and 3.
The conversion resolution is set to 9 bits i. Both trim values are 0x00, resulting in wrong temperatures i. Once trim values are set to something reasonable, the time for temperature conversion is within the range specified for Family A above. ROM pattern : sstt-tt-tt-crc, ssss-tt-tt-tt-crc, sstt-ttcrc The chips follow the description of Family A1 above with the following exceptions : The ROM pattern is incompatible with what Maxim produces.
Note that this means the curve parameter is 0x1f, i. Also, the offset parameter spreads over units rather than a range typical for Family A1 . The time for temperature conversion spans a remarkably wide range from to ms between chips .
This range remains wide and outside the bounds of Family A1 even when applying more recent trim settings . Conversion time increases noticably with temperature approx. Anecdotally: error seems to be smaller at higher temperatures . Alarm settings i. Some chips retain their scratchpad content across a ms power cycle.
One specimen tested did not function properly in parasitic mode. The topmark is printed rather than lasered, and there is no mark in the indent.
DS18B20 sensor de temperatura para líquidos con Arduino
You can use the preceding links or go directly to MakerAdvisor. Schematic The sensor can operate in two modes: Normal mode: 3-wire connection is needed. You provide power to the VDD pin. The sensor derives its power from the data line. Follow the next steps to install those libraries. Installing Libraries 1. The Library Manager should open.
Interfacing DS18B20 1-Wire Digital Temperature Sensor with Arduino